The present application relates to information processing apparatuses, information recording media, information processing methods, and computer programs. More specifically, the present application relates to, for example, an information processing apparatus, an information recording medium, an information processing method, and a computer program for controlling usage of content in divided units in a scheme where content such as digital broadcast content is recorded on an information recording medium and the content recorded is used.
Various types of software data (hereinafter referred to as “content”), for example, audio data such as music, image data such as movies, game programs, and various application programs, can be stored as digital data in recording media, such as a Blu-ray disc®, which employs blue lasers, a digital versatile disc (DVD), a mini disc (MD), and a compact disc (CD). In particular, a Blu-ray disc®, which employs blue lasers, allow high-density recording, so that a large volume of video content or the like can be recorded at a high quality.
These various types of information recording media include read-only memory (ROM) media that has data recorded thereon in advance and that do not allow writing new data thereon and writable media that allow writing data thereon. Using a writable information recording medium, for example, a user can receive content through digital data broadcasting, write the content received on the information recording medium, and play back and use the content.
Generally, the copyrights and distribution rights of many items of content, such as broadcast content, music data, and image data, are owned by creators or vendors of the content. Accordingly, when distributing the content, usually, certain usage restrictions are imposed, i.e., only authorized users are permitted to use the content so that unauthorized copying or the like is prohibited.
Digital recording apparatuses and recording media allow repeated recording and playback of, for example, image or sound without degrading the quality thereof. Accordingly, the distribution of illegitimately copied content via the Internet, the distribution of what are called pirate discs manufactured by copying content on CD-Rs or the like, or the use of copied content stored on hard discs of personal computers (PCs) or the like causes the problem of copyright infringement.
A high-capacity recording media, such as a DVD or a type of recently developed recording medium employing blue lasers, can record a large volume of data, for example, corresponding to one or several movies, on a single medium in the form of digital information. As it becomes possible to record video information or the like in the form of digital information, it becomes increasingly important to protect copyright owners by preventing unauthorized copying. Recently, in order to prevent unauthorized copying of such digital data, various techniques for preventing illegitimate copying have been implemented in digital recording apparatuses and recording media.
For example, a content scramble system is employed for DVD players. In the content scramble system, video data, audio data, or the like is recorded on a DVD-ROM in an encrypted form, a key for decrypting the encrypted data is assigned to a DVD player having a license. The license is provided to a DVD player that is designed so as to comply with predetermined operation rules, such as not performing unauthorized copying. Thus, the DVD player having the license can play back image and sound from the DVD-ROM by decrypting the encrypted data recorded on the DVD-ROM using the key assigned.
On the other hand, a DVD player not having a license is not allowed to playback the encrypted data recorded on the DVD-ROM since the DVD player does not have the key for decrypting the encrypted content. As described above, in the content scramble system, a DVD player that does not satisfy certain conditions at the time of licensing is not allowed to play back digital data recorded on a DVD-ROM, so that unauthorized copying is prevented.
A scheme for controlling usage of content through encryption of content in recording and playback of content on and from an information recording medium that allows recording data thereon is described, for example, in Japanese Unexamined Patent Application Publication No. 2003-116100.
Content that is recorded on information recording media include various types of content. Thus, a scheme in which usage of pieces of content is managed individually, for example, in which usage of pieces of content is managed in different modes according to content providers, is desired. Furthermore, a scheme of management has not been established for processing of an encryption key that is executed when stored content is changed as in a case where content is moved. That is, existing systems are not sufficiently convenient for content management and key management.
Japanese Unexamined Patent Application Publication No. 2004-72342 discloses a scheme of deleting an encryption key used for decryption when a move is executed. However, when an encryption key is managed as a file that can be manipulated by a user, it is not necessarily safe enough to simply “delete” the encryption key saved in the file. That is, when the encryption key is deleted logically instead of physically, or when physical deletion is not complete, decryption could be possible if data of the encryption key remains on the disc.
There is a need for an information processing apparatus, an information recording medium, an information processing method, and a computer program for individually controlling usage of pieces of content, such as content stored on an information recording medium or content recorded by a user, and for allowing strict management of encryption keys even when content stored is changed, for example, when content is moved.